Oxygen is essential to human life. Without oxygen, human cells cannot carry out their basic metabolic functions and will eventually die. As the cells die, the human organs and tissues (which are made up of cells) eventually cease to function. For example, depriving human brain cells of oxygen for as little as five minutes can cause brain damage or even death.
The process by which humans (as well as other animals) take in and utilize oxygen is commonly referred to as "respiration." In the case of humans, respiration generally involves the continuous intake of oxygen from the air (which oxygen is then used by the cells) and release of by-products such as carbon dioxide to the outside environment. Inhalation or breathing allows the oxygen to enter the body and travel to the lungs, where it permeates the membranes of the lungs and eventually passes into the blood. The oxygen-laden blood then carries the oxygen throughout the body and, more particularly, to the cells that require it in order to sustain the living tissues and organs of the human body. As it reaches the cells, the blood exchanges its oxygen for the by-products of cellular metabolism, such as carbon dioxide. As it returns the to region of the lungs, the blood transports the carbon dioxide released by the cells. The carbon dioxide leaves the blood, enters the lungs and is released to the outside environment by exhalation. Upon release of carbon dioxide, the blood absorbs additional oxygen and the cycle is repeated.
The respiratory system facilitates the above-described exchange of oxygen for carbon dioxide. The human respiratory system is made up of a network of passageways that allows oxygen to enter the body and eventually make its way to the lungs. For example, during inhalation, oxygen is drawn in through the nostrils of the nose, from where it enters the nasal cavity. From the nasal cavity it travels through a region known as the pharynx which is located generally near the jaw region of the human. From the pharynx, the oxygen travels to the trachea, a passageway near the throat, and ultimately enters the lungs where the above-described cycle of oxygen absorption and carbon dioxide release takes place.
In humans, the nasal passageway is separated from the oral passageway (i.e. the mouth and mouth cavity) by a skeletal/muscular structure called the palate. The palate is made up of an anterior (front) bony hard palate and posterior (rear) soft palate. The nasal and oral passageways remain separated from each other except, for example, near the region of pharynx where the oral passageway intersects the nasal passageway. Thus, blockage of the nasal passageway upstream of the intersecting point would still allow for the intake of oxygen by breathing through the mouth and, thus, maintaining satisfactory respiratory function. However, obstruction of the pharynx at or near the point of intersection prevents oxygen inhaled through either the nose or the mouth from reaching the lungs.
Such obstruction near the pharynx often occurs at rest or during sleep, when the muscles of the human are in a relaxed state. For example, during relaxation, such as during sleep, the muscles of the neck and jaw relax causing the tongue to fall toward the soft palate. Also, as the muscles of the jaw relax, the chin falls toward the chest, causing the soft tissue of the soft palate to contact and close off the posterior pharynx, thereby causing a mild to moderate airway obstruction.
Typically, in an effort to overcome this obstruction, the diaphragm contracts and the chest muscles expand the chest with much strength, in an attempt to cause inspiration. These muscles then relax, usually after one to three seconds of effort, whether or not any air was exchanged into the lungs. This gives the appearance of breathing even though no air is moving into and out of the lungs. This may sometimes be described as a "false breath" or "obstructed breath". Typically as a person's oxygen levels fall, the urge to breathe becomes progressively stronger until air is exchanged (or the person expires). The strong inspiratory effort described above causes the relaxed structures (e.g. soft palate) described above to flap noisily when the inspiratory effort overcomes the obstruction. This is commonly known as a snore.
After several false breaths (sometimes referred to as sleep apnea), the arterial oxygen levels in the person fall to levels which cause the person to consciously or unconsciously open their airway in order to get air. This is an extremely strong drive which is basic to life. A person will awaken to a sufficient level to which breathing is possible. In some persons a small movement of the head or neck will open the airway. Others need to awaken almost completely in order to allow the increased muscle tone and/or head or neck movement to open the airway. Often at this point, the person may appear confused or startled, and may move about in order to get air into their lungs and thereby stay alive.
Keeping the airways open is of particular concern during surgical procedures where an anesthetic has been administered (typically by an anesthesiologist or an anesthetist) to cause muscle relaxation and sleep in the human patient. Administration of a general anesthetic causes the muscles of the body to relax, which often results in constriction of the posterior pharynx and closing of the airway in the manner described above.
During surgeries that utilize general anesthesia the respiratory drive is often sufficiently reduced to the point that a patient may show a greatly decreased response to hypoxia (or lowered blood oxygen levels). If the airways are allowed to become (and remain) obstructed, the patient may quietly expire.
One way of keeping the air flow moving is to insert an endotracheal tube (ETT) via the patient's mouth, thereby allowing air to enter the lungs through the mouth. This procedure is often referred to as "intubating." Unfortunately, intubating using an ETT or other similar device is not without its drawbacks. For example, removal of the ETT can sometimes cause irritation of the throat and, more specifically, of the vocal chords. Such irritation can result in spasm of the vocal chords (sometimes referred to as laryngeal spasm), which may require emergency treatment by the anesthesiologist.
Where an ETT is not used, ensuring that the air passageways remain open and unobstructed is done manually by the physician-anesthesiologist or the nurse-anesthetist. Keeping the air passageway open often requires the anesthesia provider to tilt and hold the chin of the patient in a backward fashion to avoid having the soft palate constrict the posterior pharynx as described above. During long surgical procedures, the continuous holding of the chin can become quite tedious and uncomfortable for the anesthesia provider.
Another concern during surgeries is the sudden reaction of a patient to air obstruction. Obstruction of the posterior pharynx may, in some patients (particularly those with thick necks, large tongues or those that are obese), occasionally cause such patients to suddenly awake or move as they attempt to open the blocked airway. Such sudden movements are at the very least, distracting to the surgeon performing the procedure and, in cases where the surgery is particularly delicate, such as in cataract surgery, may be quite dangerous.
Thus, it would be desirable to provide an apparatus that will keep the air passageways of a patient open and, at the same time, relieve the anesthesia provider from the strain of having to hold the patient's chin. Beyond surgical procedures, it is also desirable to provide an apparatus that will reduce or eliminate snoring and possibly sleep apnea.